diff --git a/packages/authorization-process/src/model/domain/apiConverter.ts b/packages/authorization-process/src/model/domain/apiConverter.ts
index 7f9be19be9..418f25dea5 100644
--- a/packages/authorization-process/src/model/domain/apiConverter.ts
+++ b/packages/authorization-process/src/model/domain/apiConverter.ts
@@ -14,7 +14,6 @@ import {
   ApiKey,
   ApiKeyUse,
 } from "./models.js";
-import { missingUserId } from "./errors.js";
 
 export const ClientKindToApiClientKind = (kind: ClientKind): ApiClientKind =>
   match<ClientKind, ApiClientKind>(kind)
@@ -48,23 +47,17 @@ export function clientToApiClient(
     createdAt: client.createdAt.toJSON(),
     purposes: client.purposes,
     kind: ClientKindToApiClientKind(client.kind),
-    description: client.description ? client.description : undefined,
+    description: client.description,
     ...(includeKeys ? { keys: client.keys } : {}),
   };
 }
 
-export const keyToApiKey = (key: Key): ApiKey => {
-  if (!key.userId) {
-    throw missingUserId(key.kid);
-  } else {
-    return {
-      name: key.name,
-      createdAt: key.createdAt.toJSON(),
-      kid: key.kid,
-      encodedPem: key.encodedPem,
-      algorithm: key.algorithm,
-      use: KeyUseToApiKeyUse(key.use),
-      userId: key.userId,
-    };
-  }
-};
+export const keyToApiKey = (key: Key): ApiKey => ({
+  name: key.name,
+  createdAt: key.createdAt.toJSON(),
+  kid: key.kid,
+  encodedPem: key.encodedPem,
+  algorithm: key.algorithm,
+  use: KeyUseToApiKeyUse(key.use),
+  userId: key.userId,
+});
diff --git a/packages/authorization-process/src/model/domain/errors.ts b/packages/authorization-process/src/model/domain/errors.ts
index 2530f10b03..c98ab058c2 100644
--- a/packages/authorization-process/src/model/domain/errors.ts
+++ b/packages/authorization-process/src/model/domain/errors.ts
@@ -1,18 +1,9 @@
-import { ApiError, makeApiProblemBuilder } from "pagopa-interop-models";
+import { makeApiProblemBuilder } from "pagopa-interop-models";
 
 export const errorCodes = {
   clientNotFound: "0001",
-  missingUserId: "0002",
 };
 
-export function missingUserId(kid: string): ApiError<ErrorCodes> {
-  return new ApiError({
-    detail: `Key ${kid} has not UserId`,
-    code: "missingUserId",
-    title: "Missing userId",
-  });
-}
-
 export type ErrorCodes = keyof typeof errorCodes;
 
 export const makeApiProblem = makeApiProblemBuilder(errorCodes);
diff --git a/packages/models/src/authorization/protobufConverterFromV2.ts b/packages/models/src/authorization/protobufConverterFromV2.ts
index 674ad146bf..36671661db 100644
--- a/packages/models/src/authorization/protobufConverterFromV2.ts
+++ b/packages/models/src/authorization/protobufConverterFromV2.ts
@@ -38,6 +38,6 @@ export const fromClientV2 = (input: ClientV2): Client => ({
   purposes: input.purposes.map((purposeId) => unsafeBrandId(purposeId)),
   users: input.users.map(unsafeBrandId<UserId>),
   kind: fromClientKindV2(input.kind),
-  createdAt: bigIntToDate(input.createdAt!),
+  createdAt: bigIntToDate(input.createdAt),
   keys: input.keys.map(fromKeyV2),
 });